Sun-bleached skeletons of long-dead whitebark pine trees stand at the top of a 7,200-foot-high ridge along the Reservation Divide on the Flathead Indian Reservation, Montana. With annual average temperatures in Montana rising, the whitebark pine that were not previously threatened are now facing an increase in blister rust infections, mountain pine beetle infestations and wildfire.

Stretching from British Columbia, Canada down to parts of California and east to Montana, live the whitebark pine. The tree grows in subalpine and timberline zones — elevations anywhere from 4,000 to almost 9,000 ft. It's an unforgiving space. The wind is harsh. Plants and animals confront sub-freezing temperatures, often until summertime.

The whitebark pine has historically thrived in these lands. But today, the tree species is in trouble. So much so that the U.S. Fish and Wildlife Service listed the whitebark pine as a threatened species in December 2022. Increased fire intensity from climate change and colonial fire suppression practices, infestation by mountain pine beetles and a deadly fungus called blister rust — they're collectively killing this tree.

According to the research, the levels of mercury found in Arctic foxes depend on their diets Scientists say that foxes in Arctic regions who feed on ocean prey are being exposed to dangerous levels of mercury. On one Russian island where the population of foxes has crashed, the researchers believe the toxin has played a key role in the decline. They say the findings could have important implications for conservation. The data is published in the Journal, PLOS ONE. Mercury levels in the world's oceans have doubled over the past 100 years, according to the UN, with more mercury deposited in the Arctic than on any other part of the planet. The Arctic Council says there has been a ten-fold increase in the levels of mercury found in top predators in the region over the past 150 years. Hair of the dog Now a team of researchers says it has found significant levels of mercury in different populations of Arctic foxes in different environments. On the small Russian island of Mednyi, part of the Commander Islands chain in the North Pacific Ocean, the foxes survive almost exclusively on sea birds with some also eating seal carcasses. The island's fox population declined mysteriously in the 1970s, and while the population is currently stable many of them are in poor condition, and have low body weight. They are listed as a critically endangered species with IUCN. Scientists at one time believed their shrinking numbers were caused by an infection, but they couldn't find the underlying cause.